Give examples and suggest reasons for the following features of the transition metal chemistry.
  (i) The lowest oxide of transition metal is basic, the highest is amphoteric / acidic.
(ii) A transition metal exhibits highest oxidation state in oxides and fluorides.
(iii) The highest oxidation state is exhibited in oxoanions of a metal.

Explanation

(i) Acidic strength of oxides increases with the increase in oxidation state of the element e.g. `MnO(Mn^(2+))` is basic whereas `Mn_2O_(7)(Mn^(7+))` is acidic in nature.
(ii) Both oxygen and fluorine being highly electronegative can increase the oxidation state of a particular transition metal. In certain oxides, the element oxygen is involved in multiple bonding with the metal and this is responsible for the higher oxidation state of the metal.
(iii) This is also due to high electronegativity of oxygen e.g., chromium exhibits oxidation states of +6 in oxoanion `[CrO_(4)]^(2-)` and manganese shows oxidation state of +7 in oxoanion `[MnO_4]^(-)`.